A tiny, scaleless, freshwater fish, the highly endangered unarmored threespine stickleback is a fierce protector of its nest, which it defends by dashing forward with gaping mouth and “hackles” raised. Only two inches long, and bright-red when mating, male sticklebacks patch their nests together with mucus threads spun from their kidneys, then leap out eagerly to find egg-carrying females. When the egg laying is done, however, females are unceremoniously ejected from the premises.



The unarmored threespine stickleback was listed as endangered in 1970 under the precursor to today's Endangered Species Act. Critical habitat was proposed for the species by the U.S. Fish and Wildlife Service in 1980, but never designated.

In 2002 the Center filed a lawsuit to protect habitat for the stickleback, since the Service had failed to finalize its more than 20-year-old proposal. Unfortunately, we lost the suit when the Service “finalized” the proposal by withdrawing it; further legal options were preempted by the fact that the species had first been listed prior to 1978, when the critical habitat provision of the Act was changed from discretionary to mandatory.

We helped oppose a large mine proposed by Cemex in the Santa Clara watershed, bringing new attention to the plight of the river and its dependent wildlife; the court went against the stickleback in the case, holding that critical habitat for the fish was discretionary, not mandatory, due to the timing of the species' initial listing. As a result, the Center is working in other ways to help save the stickleback: we continue to watchdog development on the river and advocate for the tiny, pugnacious fish through our work to protect Southern California watersheds and forests.

Photo © Warwick Sloss/